Process for the production of oligourethanes containing mercapto groups and their use as binders for coating and sealing compositions hardenable by oxidation and as additives for epoxide resins

Abstract

The invention relates to a process for the production of oligourethanes containing terminal mercapto groups by reacting 1-isocyanatomethyl-1,3,3-trimethyl-5-isocyanatocyclohexane with substoichiometric quantities of relatively high molecular weight polyether polyols and mercapto ethanol and to the use of the oligourethanes obtainable in this way as binders for coating and sealing compositions hardenable by oxidation and as additives for epoxide resins.

What is claimed is: 
     
       1. A process for the production of oligourethanes containing terminal mercapto groups which comprises reacting (a) 1-isocyanatomethyl-1,3,3-trimethyl -5-isocyanatocyclohexane with   (b) substoichiometric quantities of a polyether polyol having a theoretical molecular weight of about 4000 to 7000 and an average OH-functionality of greater than about 2.5 and   (c) about 0.8 to 1.1 times the equivalent quantity of mercapto ethanol, based on the excess of isocyanate groups arising out of the molar ratio of components (a) to (b) and the hydroxyl groups of component (c).   
     
     
       2. The process of claim 1, wherein an NCO-prepolymer is initially prepared from components (a) and (b) at an NCO/OH-equivalent ratio of from about 1.8:1 to 3:1 and is then reacted with component (c). 
     
     
       3. The product of claim 1 or 2. 
     
     
       4. A coating or sealing composition which is hardenable by oxidation and contains as binder the product of claim 3. 
     
     
       5. A composition comprising (a) epoxide resins and   (b) the product of claim 3.